Evidently buried again. Was looking for a way up the nearby summit, but seeing 3 trig symbols on the GPS (I'd already been to the FBM) I thought I'd have a look. Got the rivet OK but no sign of this; lacked the motivation to get the trowel out of the car - well it's only a bertnsen :-)

Bernsten, buried in verge on roadside, just in front of the Gwynfryn road sign. The old Wrexham FBM is across the other side of the main road, and the Gwynfryn bolt is a bit further down the lane. They'd cut the grass, so not much digging required